1.4 Sea-Floor Spreading



Vocabulary


Mid-Ocean Ridge: The undersea mountain chian where new ocean floor is produced;a divergent plate boundary.
Sonar: A system that determines the distance of an object under water by recording echoes of sound waves; get its name sound waves navigation and ranging.
Sea-Floor Spreading: The process by which molten material adds new oceanic crust to the ocean floor.
Deep- Ocean Trenches: A deep valley along the ocean floor through which oceanic crust slowly sinks towards the mantle.
Subduction: The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary.

Outline



Mapping the Mid-Ocean Ridge

  • The East Pacific rise is a part of the mid-ocean ridge

Evidence For Sea-Floor Spreading

  • Evidence from molten material
    • Evidence from magnetic stripes
      • Evidence from drilling samples


Subduction at deep-ocean trenches

  • Subduction in the Pacific Ocean
    • Subduction in the Atlantic Ocean